A flat work ironer is a machine used in commercial or industrial laundries which serve large institutions such as hotels, hospitals, or restaurants to mechanically heat and press flat items such as bed linens, aprons, table linens, etc. The machine has a series of parallel rolls which are positioned in complementary-shaped semi-cylindrical polished seats formed in a chest that is heated by means of gas, steam, or thermal liquids such as hot oil.
The ironer functions by causing the flat work to be pressed between the heated chest and each roll in succession. The complementary shape of the rolls versus the shapes of the polished seats of the heated chest causes the flat work to be retained in contact with the heated chest longer than it would be if the heated chest were flat, so as to cause the moisture in the flat work to quickly evaporate and to remove the folds and wrinkles from the flat work. The chest typically is heated to and maintained at a temperature of at least approximately 300.degree. F. but may reach temperatures of up to 450.degree. F. The flat work typically is partially wet after having been washed and spun to a damp condition and is fed in at one end of the ironer by a surface conveyor, passed between the heated chest and the rolls and exits at the other end of the ironer in a substantially dry and wrinkle-free condition.
Typically, the rolls are fabricated of stainless steel and are hollow with a perforated cylindrical skin and perforated end walls to allow for steam generated in the ironing process to pass from about the cylindrical surfaces of the rolls into the interior of the rolls where it is removed by a vacuum system through one or both of the end walls of the roll. This creates air movement through and about the flat work so as to remove the high humidity air from about the ironer. The rolls usually are wrapped with a cushioning pad and then with an outer roll cover. The cushioning pad is typically made of a thermally resistant material such as, in the past, asbestos. More recently, this material is a combination of polyester and cotton or 100% recycled aramid or a combination of recycled aramid, polyester and/or cotton.
The roll covers must be thermally stable and hydrolysis resistant to provide for a wear life of at least one year under use of at least 40 hours per week. The covers should be of adequate stiffness to ensure a wrinkle free and smooth ironing surface. However, the cover should be porous to allow for the passage of steam through the cover.
In the past, roll covers for flat work ironers have been manufactured of asbestos fabric. For example, U.S. Pat. No. 2,333,824 to Schoepf teaches a ironer roll where both the pad and the outer cover are manufactured from asbestos. U.S. Pat. No. 2,497,696 to Smith teaches a cover made of asbestos fibers adhesively applied to a underlying pad. Other covers taught by the prior art references have been composed of muslin or duck, see U.S. Pat. No. 1,539,916 to Siever, and aluminum, see U.S. Pat. No. 2,762,111 to Morgan.
U.S. Pat. No. 3,811,164 to Faress, et al teaches the use of a cover composed of a fabric which has been impregnated with a thermosetting resinous material, specifically a phenolic resin. Preparation of phenolic resins requires the use of the chemical phenol which is a hazardous substance.
There are some disadvantages to use of the roll covers as taught by the prior art. Perhaps the most obvious are the environmental and health dangers associated with asbestos and phenol. Other problems with prior art roll covers have been in attaining desired characteristics such as porosity, smoothness, heat resistance, and wear resistance. Another disadvantage to the covers now used which are made with a phenolic resin is the appearance of the roll cover. These covers are brownish-yellowish in color when made and turn a darker brown as they are used. The manufacturers of the roll covers apparently have not been able to fabricate roll covers of different colors which retain the original colors over substantially the entire lifetime of the roll cover. Thus, the overall appearance is unaesthetic and the color instability of the covers makes them inconsistent and nonuniform in appearance.